Unit V: Introduction to PERT/CPM

Introduction to Project Management:Project: “an organized undertaking”

Master of Engineering Thesis ProjectFinding a jobBuilding a porch Buying a house Design and manufacture a car (Large Program)Put a man on the moon (Huge Program)

DefinitionA project is composed of jobs, tasks or functions and activities that are related to

each other. Every project has one specific purpose and required resources like men, money, materials, machinery, minutes, etc. To plan, implement, and control the management of large, one time projects. Applicable in Construction, Shipbuilding, Weapons Systems Development, etc.–Applies to uncertain technology projects–Applies to variable cost resource allocationProject Characteristics

o Single unito Many related activitieso Difficult production planning & inventory controlo General purpose equipmento High labor skills

Examples of Projectso Building constructiono New product introductiono Training seminaro Research project, etc.

Objective of a project:o The project should complete within elapsed time o It should use optimum resources without delayo It should complete with a minimum of capital investment.

Project Management:Project Management is the application of knowledge, skills, tools and techniques

to project activities in order to meet project requirements.

Project Management: - a discipline "Art and Science".o is an arto is a science and has a set of tools and methods

Qualities of Project Manager:Effective Project Manager should have the following qualities:

1

o Lead by exampleo Visionarieso Technically competento Decisiveo Good communicatorso Good motivatorso Stand up to execs when necessaryo Support team memberso Encourage new ideas

Alternate view of Effective Project Managers:o Leaders (also managers, administrators)o Level headedo Communicatorso Goal orientedo Problem solvers (prioritization)o Innovatorso Work well under pressure (able to laugh)o Technically competent, respected, awareo Know company & its business

Project Management Objectiveo To achieve the project goal effectively and efficientlyo To keep customers happyo To keep the team focus on the goal o To make sure that team members work wello To share workload everyone equally

Project Management involves the following three phases:1. Project Planning

project organizing2. Scheduling3. Controlling

1) Project Planning: - Project plan is a map and a guide and benchmark to measure progress.

o Establishing objectiveso Defining projecto Creating work breakdown structure (WBS)o Determining resourceso Forming organization

Project Organizationo Often temporary structureo Uses specialists from entire companyo Headed by project manager

2

o –Coordinates activities o –Monitors schedule & costs

o Permanent structure called ‘matrix organization’

2) Project Schedulingo Sequencing activitieso Identifying precedence relationshipso Determining activity times & costso Estimating material & worker requirementso Determining critical activities

3) Project Controlling

Project Goal Setting --What do we want to achieve? | V

Performance Measure -- What is happening? | V

Performance Test -- Why is it happening? | V

Corrective Action -- What should be done?

Project Management Techniques:I. Gantt chart

II. Network Techniques • Critical Path Method (CPM)• Program Evaluation & Review Technique (PERT)

I) Gantt chart:

Henry Laurence GanttHenry Laurence Gantt (1861-1919) was a mechanical engineer and management

consultant who is most famous for developing the Gantt chart in the 1910s. These Gantt charts were employed on major infrastructure projects including the Hoover Dam and Interstate highway system.

Henry Laurence Gantt's legacy to management is the Gantt chart. Accepted as a commonplace project management tool today, it was an innovation of world-wide importance in the 1920s. But the Chart was not Gantt's only legacy; he was also a forerunner of the Human Relations School of management and an early spokesman for the social responsibility of business.

Life and carrier Henry L Gantt was born into a family of prosperous farmers in Maryland in 1861.

His early years, however, were marked by some deprivation as the Civil War brought

3

about changes to the family fortunes. He graduated from Johns Hopkins College and was a teacher before becoming a draughtsman in 1884 and qualifying as a mechanical engineer. From 1887 to 1893 he worked at the Midvale Steel Company in Philadelphia, where he became Assistant to the Chief Engineer (FW Taylor) and then Superintendent of the Casting Department. Gantt and Taylor worked well in their early years together.Gantt chart

During the era of scientific management, Henry L. Gantt developed a tool for displaying the progression of a project in the form of a specialized chart. An early application was the tracking of the progress of ship building projects. Today, Gantt's scheduling tool takes the form of a horizontal bar graph and is known as a Gantt chart, a basic sample of which is shown below:Gantt chart FormatExemplary Gantt chart for building a house:

Duration : Jan. Feb. Mar. Apr. May. Jun. Jul.1 activity 2 activity3 activity

The horizontal axis of the Gantt chart is a time scale, expressed either in absolute time or in relative time referenced to the beginning of the project. The time resolution depends on the project - the time unit typically is in weeks or months. Rows of bars in the chart show the beginning and ending dates of the individual tasks in the project.

In the above example, each task is shown to begin when the task above it completes. However, the bars may overlap in cases where a task can begin before the completion of another, and there may be several tasks performed in parallel. For such cases, the Gantt chart is quite useful for communicating the timing of the various tasks.

For larger projects, the tasks can be broken into subtasks having their own Gantt charts to maintain readability.

4

Gantt chart EnhancementsThis basic version of the Gantt chart often is enhanced to communicate more information.

o A vertical marker can used to mark the present point in time.o The progression of each activity may be shown by shading or hatched lines in the

bar as progress is made, allowing the status of each activity to be known with just a glance.

o Dependencies can be depicted using link lines or color codes.o Resource allocation can be specified for each task.o Milestones can be shown.

Gantt chart Role in Project PlanningFor larger projects, a work breakdown structure would be developed to identify

the tasks before constructing a Gantt chart. For smaller projects, the Gantt chart itself may used to identify the tasks.

The strength of the Gantt chart is its ability to display the status of each activity at a glance. While often generated using project management software, it is easy to construct using a spreadsheet, and often appears in simple ASCII formatting in e-mails among managers.

For sequencing and critical path analysis, network models such as CPM or PERT are more powerful for dealing with dependencies and project completion time. Even when network models are used, the Gantt chart often is used as a reporting tool. Editorial note: The name of this tool frequently is misspelled as "Gannt" or “Gant”. The correct spelling is "Gantt."

II) Network Techniques:Network Techniques help in designing, planning, organizing, coordinating,

controlling and in decision making in order to complete the project economically in minimum available time and limited available resources.

More popular Techniques of Network are:CPM Critical Path MethodPERT Programme Evaluation and Review Method LCS Least Cost MethodRAMS Resource Allocation and Multi-project SchedulingMAP Manpower Allocation ProcedureRPSM Resource Planning and Scheduling MethodGERT Graphical Evaluation and Review Technique

Characteristics of network diagram:

Advantages of network analysis:

Limitations of network analysis:

Objectives of network analysis:

5

Features of network Techniques: o Logical base for project planning o Simple in nature (straight forward in concept)o Improves coordination and communication o Highlights Trouble spots and pinpoints responsibilities of a project managero Wider in applicationo Anticipates unforeseen changes in futures o Used in Construction, Shipbuilding, Weapons Systems Development, etc.

o Applies to uncertain technology projectso Applies to variable cost resource allocation

Applications of network analysis:

Network Diagram Representation in arrow diagram and CPM / PERT:Network representations of a project, certain basic terms and their definitions are used:1) Activity: – any individual operation, which utilizes resources and time, and has an end and a beginning. An arrow is commonly used to represent an activity with its head indicating the direction of progress in the project. These are usually classified into following four categories: 

     Predecessor activity: - activities that must be completed immediately prior to the start of another activity.

     Successor activity: - activities that cannot be started until one of more of other activities are completed, but immediately succeed them.

     Concurrent activity: - activities which can be accomplished concurrently. It may be noted that an activity can be a predecessor or a successor to an event or it may be concurrent with one or more of the other activities.

     Dummy activity: - it is an imaginary activity which does not consume any kind of resource but merely depicts the technological dependence. It is represented as broken arrow. Dummy activity is inserted in the network to clarify the activity pattern in the following situations:a)      To make activities with common starting and finishing point distinguishable b)      To maintain unique number system for different activitiesc)      To keep the logical sequence of activities and their inter relationshipd)     To identify and maintain the proper precedence relationship between activities

Dummy activities are used in the following situations:Fig. (A) Represents: If p and q activities are concurrent and Activity r is successor of activity q.

 Fig. (B) Represents: If activities a and e are concurrent; Activity b is after a and e, and activity f is after activity e.

 Jobs l and m in a certain project must precede the job n. On the other hand, the

job o is preceded by the job m only. Fig. (C1) shows the incorrect way since, though the relationship between l, m and n are correct, the diagram implies that the job must be

6

preceded by both the jobs l and m. The correct representation using the dummy d is shown Fig. (C2) obvious that indicated precedence relationships are justified. 2) Event: – An even represents a point in time signifying the completion of some activities and the beginning of new ones. Except starting and finishing event, remaining all events are dual role events in the network. This is usually represented by circle ‘O’ or any geometrical symbol in a network which also called node or connector. Event can be further classified into following three categories such as…

      Merge event: - when more than one activity comes and joins at an event.      Burst event: - when more than one activity leaves from an event.      Merge and burst event: - an activity may be merge and burst at the same time

from an event.

3) Sequencing: – the first prerequisite in the development of a network is to maintain the precedence relationship. In order to make a network, following points should be taken into consideration:

      What job or jobs precede it?      What job or jobs follow it?      What job or jobs could run concurrently?      What controls the start and finish of a job?

It is necessary that a network be drawn with full care. There are many ways to draw a network. It is generally agreed that dummy activities be used as liberally as needed in the first attempt, while revising the same network, every attempt should be made to minimize them. Some of the activities and their relations are given from the following examples: a) Sequential activities: - Activity B can not start before activity A is completed or

activity B follows activity A or activity A precedes activity B. b) Diverging activities: - Activity Q and R can not start before the completion of

activity P. Activity Q and R could be start at same time.c) Converging activities: - Activity N can not start before completion of activity L

and M, and these are the predecessor of activity N.d) Mixed activities: - Activity L and M must be completed before start of activity Q

and R. These are the successor activities of L and M and they are concurrent could start at the same time.

e) Parallel activities: - In this activity chains B follows A and F follows E but both activity chains are completely independent of each other.

 Graphical Representation of Events and Activities:

o Flow Charting - Uses Nodes and Arrows based on either in the method “Activity On Node” (AON) or “Activity On Arrow” (AOA). Most of the practitioners used method is AOA.

o Arrowso An arrow leads from tail to head directionally.

o Nodeso A node is represented by a circle.

7

1 2

Activity On Nodeo Task is represented by Node as the Completion of an Activity.o Arrows Represent the Sequential Linkages between Activitieso For Example, Node 1 is Begin, Node 2 is Complete Task 1, and Node 3 is

Complete Task 2.Example:

Activity On Arrowo Task is represented by an Arrow Bounded on Either End by a Node (Event)o Each Event is identified by a Numbero The Activity is designated by the Leading Event Number and the Following Event

Number - i.e. Activity 1 - 2Example:

Rules for drawing network diagram are summarized as follows:1)      Each activity is represented by one and only one arrow in the network.

2)      No two activities can be identified by the same end event

For example activity Z and Y (Fig. A) have the same end events. The procedure is to introduce a dummy activity either between Z and one of end events or between Y and of the end events. Modified representations after introducing dummy d are shown Fig. B. as a result of using the dummy activity d, activities Z and Y can now be identified by unique end events. It must be noted that a dummy activities does not consume any time or resources. 

3)     In order to ensure the correct precedence relationship in the arrow diagram, following questions must be checked whenever any activity is added to the network....• What activity must be completed immediately before this activity can start?• What activities must follow this activity?• What activities must occur simultaneously with this activity?

 Few important suggestions for drawing network:

1)     Try to avoid arrows which cross each other.2)      Use straight arrows.3)      Do not attempt to represent duration of a activity by its arrow length.4)     Use arrow from left to right or right to left avoid missing two direction, vertical

and standing arrows my be used if necessary.5)    Use dummies freely in rough draft but final network should not have any

redundant dummies.

8

1 2 3

1 2

6)     The net work has only one entry point or start event and one point of emergence – called the end event.

 Common errors in drawing network:Three types of errors commonly observed they are…

1) Dangling : - to disconnect and activity before the completion of all activities in a network diagram is known as dangling error. This is shown in the following diagram. Here Dangling activity is 2 – 5.

2) Looping or Cycling : - drawing an endless loop in a network is known as looping error as shown in the following figure.

3) Redundancy : - unnecessarily inserting the dummy activity in network logic is known as error of redundancy. Shown, in the diagram activity 2 – 4.

 Labeling the events or node by Dr. Fulkerson’s Rules:A standard procedure called I – J rules developed by Dr. D R Fulkerson: - They are…

I. A start event is the one which has arrows emerging from it but none entering it. Find the start event and number it as one

II. Delete all arrows emerging from all numbered events. This will create at least one new start event out of preceding events.

III. Number all new start events 2, 3, 4, … and so on (no definite rule is necessary, but numbering from ‘top to bottom’ may facilitate other users in reading

the network when there are more than one new start events).IV. Go on repeating steps number 2 and 3 until the end is reached.

 Now consider the following network diagram for labeling by Fulkerson’s rule.

To number the nodes using Fulkerson’s rule, numbering of nodes 1 and 2 is obvious. Apply step II. The bottom node is the only node from jobs which is emerging out but none entering it. This is number 3. Applying step II again, node number 4 is easily obtained and likewise 5 can also be determined.

Using step II again, there are two starting points, and either one of them could be numbered 6. Keeping in view the case of numbers 4, 5 and 6 all in a row, the top node is numbered 6. Rest of the numbering procedure is simple and the complete network with numbers is shown in the following figure.

Numbering the events by DR. Fulkerson’s rules:1) There is a single initial event in the net work diagram. This initial event will

have arrows coming out of it and none entering it. Number this initial event as 1.2) Neglect all the arrows emerging out of the initial event numbered 1. Doing so, it

will apparently provide one or more new initial events. 3) Number these apparently produced new initial events as 2, 3, 4 … etc.4) Again neglect all emerging arrows from these numbered events. This will create

few more initial evens.5) Follow rule – 3.6) Continue this operation until the last event, which has no emerging arrows, is

numbered.

9

A

B

C

D

E

F

G

H

I

J Kd

The importance of good numbering procedure can hardly be claimed in a simple network, but the Fulkerson’s procedure has cetin distinct advantages when network is large.

First, the Fulkerson’s producer will always detect a close loop in the network if there is any. In network methods, a close loop represents an impossible event.

Second, numbers are smaller toward the start side and become larger on the end.

Third advantage will become apparent when a matrix representation of the network is brought for computerization.

 

10